Indeed, that's why I said "almost free". And yeah, the acquisition of ASICs can be difficult too but not impossible for a government (they can reclaim whatever and even coordinate with other states).
Coordinating multiple governments is a hard enough tasks, coupled with potential conflict of interests between them.
China actually controls about 65% of the hashrate, based on CBECI's research BUT that is based on a sampling of several mining pools which are pretty much all based in China so take it with a pinch of salt. If you're talking about controlling the current 51% of the hashrate, it is already possible for certain states to have that much within their geographical boundaries but coercing and coordinating an attack, especially with such a huge and diversed region like China could be very difficult.
If you're thinking of the government purchasing them, it is possible but it would be a terrible idea. It would be useless after an attack.
But neverthless, the biggest obstacle to a successful long-lasting 51% attack is the energy consumption. And in a hypothetical future where nation-states has the monopoly of nuclear fusion energy production, they can use that advantage to do such attacks.
Bitcoin's energy consumption is not excessively big, not that current infrastructure cannot support it and I predict by the time nuclear fusion becomes practical, the cost and efficiency of other forms of energy would've probably increased as well. 51% attacks
cannot be sustained over long periods of time; after a single attack, the community would react to the attack accordingly and probably render the ASICs useless. There is no point in sustaining such an attack and given Bitcoin's total market cap, any 51% attack would be purely political as the cost would probably be greater than the benefits and that the GDP of a single country is likely greater than what they stand to gain financially from such an attack.
But, if you're talking about countries like North Korea then they probably would be incentivised financially. Given their energy situation, its safe to say that they're far from a threat.